If you have ever lived with older dogs, I’d be willing to bet that you have some experience with lipomas.
Lipomas are benign tumors derived from fat cells. They are usually located under the skin. They often develop very quickly (seemingly overnight in some cases), but then they don’t do much. Maybe they’ll grow or shrink a little with weight gain or loss, but that’s about it. Lipomas usually don’t cause dogs many problems, unless they are exceptionally large or are in a location where they adversely affect a dog’s mobility or other body functions.
Lipomas can’t be differentiated from other subcutaneous masses by appearance alone, so I always recommend to my clients that we check out any new lumps on their dogs with a needle aspirate and a cytological exam of the cells I draw off. Fat has a very characteristic appearance under the microscope. So, if all I see is fat, and everything else points to the mass behaving like a lipoma, I am comfortable calling it a lipoma.
I had a pathology professor in veterinary school who strongly recommended (to put it mildly) that every lipoma should be surgically removed except under the rarest of circumstances. After being a veterinarian for a while, I had to wonder whether he had ever been in general practice. I routinely see older dogs that seem to be members of the "lipoma of the month" club.
The professor’s point was that if you had a fatty tumor on your body, wouldn’t you want it taken off? True enough, but I don’t think that surgery after surgery would really be in the best interests of some of these elderly dogs. I always offer the option of surgery to my clients, and strongly recommend it in cases where I think the mass is bothering a dog, but treatment should always be individually tailored. By not removing every fatty mass and sending it off for analysis, I do accept a small amount of risk that I could be missing a liposarcoma — an aggressive, cancerous tumor of fat — but liposarcomas are actually quite rare (I remember one in the last 12 years).
Recently, a small study looking into using liposuction to remove lipomas was published in the Journal of Small Animal Practice. What a cool idea, and the outcomes were pretty good. Using suction equipment that most veterinary practices already have on hand, the researchers removed 76 lipomas from 20 dogs. The procedure was successful in 73 cases (96%). Really big lipomas, those that infiltrated surrounding tissues or contained a lot of fibrous tissues, and masses in the groin area did not respond as well as did those that were surrounded by a capsule and were under 15 cm in diameter.
Regrowth did occur in 28 percent of the locales, but liposuction is much less invasive than traditional surgical methods, so it is still an attractive option, particularly in those dogs that have multiple lipomas.
Dr. Jennifer Coates